code: def check_for_orphans(graph):
      msg = (
          "Step *{0.name}* is unreachable from the start step. Add "
          "self.next({0.name}) in another step or remove *{0.name}*."
      )
      seen = set(["start"])
  
      def traverse(node):
          for n in node.out_funcs:
              if n not in seen:
                  seen.add(n)
                  traverse(graph[n])
  
      traverse(graph["start"])
      nodeset = frozenset(n.name for n in graph)
      orphans = nodeset - seen
      if orphans:
          orphan = graph[list(orphans)[0]]
          raise LintWarn(msg.format(orphan), orphan.func_lineno)
  
imports: import re
  from .exception import MetaflowException
  from .util import all_equal
label_desc: Use image node_id 10 for calling a global function with example usage: check_for_orphans(graph) without return types